I'm about to suggest some ridiculous bullshit.
If DB is intent on wrestling again, then could it be that his injuries are not as severe as people assume? Maybe that WWE, while eager to have him in a non-wrestling role so they can enjoy his popularity and amiable on-screen persona, are also happy to have him removed from their in-ring storylines and therefore to dissolve the audience's focus on him when they are trying to get other performers over whom they think are better suited to go on billboards and talk shows, etc?
I'm sure it would be safer for him to never wrestle again, but that's something which is always true for everybody. It might be that he isn't one suplex away from a vegetative state...but maybe the WWE is happy to have him under contract and out of the ring. Meanwhile, DB will take the money and do his best at the job he has, while biding his time for when he can go elsewhere and do what he likes to do.